Use of CPAP on flights where facemasks are mandatory
 

Has anyone traveled with their CPAP and tried to use it? I mean, you have to remove your mask to wear it, it blows air out constantly. Am I expected to stay awake the entire flight if I can't use my CPAP?

I would call the travel assistance desk and see what the protocol is.

Personally, I would not risk it unless you are willing to lose your life. If this gets in your lungs the pneumonia will put you on a vent in the icu in days.

Did you ever get an answer?
My travel cpap has a hepa filter on inbound air and I can use a full face mask, which I think would meet the criteria, I can see nasal pillows being discoursged.

I talked to UA Global Services - provided them my perscription and basically no issues since. I do take a paper mask and try to wrap it around the exhale port (I use a travel CPAP, so it is very small and the exit port is 8" down the hose) and no one has said anything. I have a note from the UA medical services people acknowledging my perscription but no FA has said anything.
I haven't flown LH, ANA or EVA since the pandemic for a sleep flight yet though.

When I saw the subject I was thinking "no way do I want somebody pumping their breath into the cabin!?"
With filters on the ports, if the mask itself doesn't leak, it seems like it'd be better than OK. Definitely keep that note with you and as a courtesy to your fellow PAX you might show your neighbor that the ports aren't just open to the cabin.

(I remember when all this was new some of the emergency "ventilators" in use were basically CPAP machines with supplementary oxygen and there was worry that they would spread the virus more than the clinical ventilators that were in short supply, but this is your personal machine not being shared.)

Happy travels!

Using a CPAP with a HEPA inlet filter might not be dangerous to you, but the equipment will aerosolize your breath and secretions and spray them into the environment in a form that will travel farther and persist longer than if just exhaled. At least, that's how it works in my hospital, where CPAP is considered an aerosolizing procedure that requires healthcare providers to take extra precautions. Possibly the plumbing on your portable device is different. Please consider securely taping some sort of surgical mask over the outlet vent (not just making a cursory attempt at wrapping it loosely). It seems likely that the FAs will not be highly trained in the physics of CPAP or classes of aerosolizing procedures; just because a FA doesn't stop you from using it doesn't mean that it's doesn't increase risk to those around you.